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Fans of DC GTAW on Al

Pangea (works for NASA) and BC on the Hobart board are big fans of DC and "lab grade" helium for heavy aluminum weldments.

I've used DC/straight Helium quite extensively in the past, but for many years now, I've found I can get my work done with AC and the addition of about 25% helium.

DC welding with Helium definitely has it's place, but when you factor in the cost of the Helium along with the higher flow rates required, your covering gas ends up costing you about 7 times as much as using Argon.

Sometimes you just got no other options though.

Yea. I know what you mean. The process has been used for years in obscure (to the public) circles. I was really thinking about the final weldments/product(s). When you use 60-70CFH of UHP+/labgrade He it costs big time! Maybe it's just me, but I love to feel the filler penetrate like it does running .040 ceriated tungsten at 140 amps on 3/4" Al. Also pushing 300+amps AC is hotter than helle (had to add an e for the forum to allow it) to me.

I am nearly 50 and can't count the bottles of high dollar He, tungsten, and filler rod I smoked up over the years. The final product and selling price was good. Now days I rarely see over 40 amps on a TIG. All I do is weld critical stuff with no tolerance for error. Good to hear your input though.

Waste of time...

Nice work Closeau!
I tigged a 3x3 stainless cube most of the way, filled it with water and welded it shut. It took a couple of trys adjusting the heat. It's full of water and hopefully won't rust. It's kinda like your picture, but SS and solid.

Nice work on your welding!

Actually it is a waste of time without helium. I have never had any luck with plain jane helium. Argon will not work with this procedure. It has to be an Ultra High Purity grade gas which costs too much to play (unless you got it like that). I used to run DC GTAW a lot on 1/2 and thicker -TX alloy because it maxed out my 300DX to run AC and it was too many passes. I like to get it done and move on to something else.

I really have not given specific settings because it is an expensive process to run. I never messed much with it except on a job to job basis. If you are really interested. look up some of my old posts. I think it is all there. If not, let me know and I can send you some specs via PM or I can post to the forum. Let me know.

Too hot

SundownIII,

High amp GTAW is very uncomfortable. I am one of those guys that keep on pushing the torch until the weld is finished or it gets too hot to run it. I miss my XMT Omptima, and 30A. My ex has or had it all. She was supposed to sell everything along with all my Dynastys, Engine drives, etc and subtract it from what I owe the settlement.

Yea man that is the way to do it if you can get away with wire. So much of what I did over the years was 3/4" through 2" -T6 flat bar bends. The runs were short (2"-6") so the DC Tig was almost perfect for the application. I have never struck an arc with the D700. I hope to soon. I think I can find one to demo soon. I cannot afford one for a while-really don't need it now.

I now see that DC tigging alum is best left to the pros not a bozo like me.

Plus even if I got high purity helium and got setup for DC tigging with helium, it woulden't make me weld any better so I'll be better served by spending the money on more blue equipment as budget allows.

sorry to bring up an old thread guys but i just got a new dyn 350 and i can't figure out what the difference between balance control vs differential current adjustment. I understand the technical difference between the two but i dont understand why i would use one over the other. if i raise the balance i will put more EN into the work piece and get better penetration and less cleaning and if i raise the EN amperage i will also get better penetration and less cleaning. so what is the point of differential amperage? why note just leave at 1:1 ratio and make my adjustments with balance?? When would i use differential adjustment instead of balance control?

sorry to bring up an old thread guys but i just got a new dyn 350 and i can't figure out what the difference between balance control vs differential current adjustment. I understand the technical difference between the two but i dont understand why i would use one over the other. if i raise the balance i will put more EN into the work piece and get better penetration and less cleaning and if i raise the EN amperage i will also get better penetration and less cleaning. so what is the point of differential amperage? why note just leave at 1:1 ratio and make my adjustments with balance?? When would i use differential adjustment instead of balance control?

If you are talking about EN/EP ratio, it is the amperage values of each. I believe it has nothing to do with balance. Balance is the time value of each polarity.

The way I see it is if balance is 70, and EN is 340 amps, EP is 280 amps, then 70% of the time of the arc is EN at 340amps(melting base), and 30% of the time is EP at 280 amps(melting the electrode/cleaning).

For me I reduce the EP to prevent tungsten erosion and meltback. I also get a more defined bead. Then I adjust my balance for desired cleaning and wet-in. Less EP works better for me on thicker alum. A more balanced EN/EP I use for thinner alum like soda cans.

You can store up to 9 different AC programs for different applications. I keep all the values stored in a small spiral notebook.

Yes, you are correct and i fully understand that. But my question still remains as to why i would do that. If im welding thin material and i want a more EP going into the tungsten why can't i just reduce my balance? Reducing my balance will also give me more EP and put more amperage into my tungsten. Does it make sense what i am saying?

Does adjust the EP/EN amperage individually do something that adjust the balance WONT accomplish? I guess that is the real question i am trying to figure out.